1. Field of the Invention
The present invention relates to a composite system for radiation therapy (equipment for radiation therapy) capable of carrying out a series of radiation therapy operations for tumor or the like, specifically, an operation of accurately performing alignment of an affected portion (equivalent to target area) to be irradiated of a patient by a CT scanner, an operation of moving the patient to an irradiation apparatus such that the affected portion is matched to an irradiation position of the irradiation apparatus (equivalent to radiation therapy apparatus), and an operation of performing irradiation to the affected portion.
In particular, the present invention relates to a composite system for radiation therapy, which includes a common bed that is used for a CT (Computer tomography) scanner and an irradiation apparatus, and also X-ray simulator (optionally used), in state that the patient lies on the common bed, at the time of moving a patient to an irradiation apparatus (e.g. linear accelerator, proton machine) such that an affected portion of the patient is matched to an irradiation position of the radiation therapy, and means for moving the patient on the common bed to a specific position of each of the CT scanner and the irradiation apparatus, and also X-ray simulator (optionally used), without any rotational movement of the common bed, thereby suppressing occurrence of a positional error caused between alignment of an affected portion and irradiation thereof, and greatly improving the control of accuracy in therapy position at the time of radiation therapy.
The present invention further relates to a composite system for radiation therapy including the common bed having an isocentric rotation function or an isocentric rotation mechanism allowing the common bed to be rotated around an isocenter position (equivalent to an irradiation center upon irradiation of a target site of a patient to irradiated at different angles), thereby allowing the effective use of the isocentric rotation mechanism not only at the time of radiation therapy but also at the time of inspection by a CT scanner, an X-ray simulator (optionally used), and the like.
2. Description of the Related Art
In radiation therapy for tumor or the like of a patient, it may be desirable to search the position of the tumor (target area) by a CT scanner in a state that the patient lies on a bed, and to irradiate, in such a correct alignment state, to the affected portion (target area). In related art equipment for radiation therapy, however, only a therapy apparatus like as a linear accelerator (irradiation apparatus) or the like is installed in a radiation therapy room, and a CT scanner for alignment is generally installed in a room separated from the radiation therapy room. Accordingly, a patient, whose affected portion has been accurately imaged or aligned by a CT scanner in a room separated from a radiation therapy room, must be moved to the radiation therapy room for irradiation by the irradiation apparatus, and therefore, the patient cannot be directly subjected to irradiation with the aligned position by the CT scanner accurately kept as it is.
The present inventor has found that the movement of a patient from a CT scanner present in a room separated from a radiation therapy room to an irradiation apparatus present in the radiation therapy room brings a positional error being as large as not negligible, and to eliminate such a positional error, the present inventor has developed an integral type composite system for radiation therapy (radiation therapy system) configured by disposing both a linear accelerator (irradiation apparatus) and an X-ray CT scanner or diagnostic type CT scanner in the same room and connecting them by means of a common bed (Japanese Laid-Open Patent Publication No. Hei-9/192245). Since that time, favorable results have been reported on radiation therapy for various kinds of tumors by using such a new integral type composite system for radiation therapy (Cancer Mar. 15, 1998/Volume 82/Number 6, p. 1062-1070).
In the above-described integral type composite system for radiation therapy, to accurately perform alignment of an affected portion of a patient by a CT scanner and match the aligned position of the affected portion to an irradiation position of a linear accelerator (irradiation apparatus), the movement of the patient from the CT scanner to the irradiation apparatus has been performed as shown in FIG. 14. The integral type composite system for radiation therapy, denoted by character A13 in the figure, includes a CT scanner 1, an irradiation apparatus 2, and a rotary bed 30, wherein a patient on the rotary bed 30 is moved between the CT scanner 1 and the irradiation apparatus 2 by rotational movement of the rotary bed 30 by an angle of 180° along a circular direction (shown by an arrow “g”) around a rotational center “r′” (the prop of the rotary type bed 30).
In the case of moving a patient by rotational movement of the rotary bed 30, however, it is required for the operator(s) to carefully handle the rotary bed so as not to cause any positional error(s). From this viewpoint, the movement of a patient by using the rotary bed has a room to be improved. The integral type composite system for radiation therapy using the rotary bed has another disadvantage that in order to check whether or not a coordinate of the CT scanner and a coordinate of the irradiation apparatus are joined to each other via the rotational movement by the rotary bed, it is required to turn the rotary bed again by an angle of 180° so as to be matched again to the CT scanner, followed by re-radiograph or re-imaging. Even in the viewpoint of control of positional accuracy, the movement of a patient by using the rotary bed has a room to be improved.
In recent years, a therapy bed having an isocentric rotation function allowing the bed to be rotated around an isocenter (irradiation center) has been used for radiation therapy. As shown in FIG. 15, an isocentric rotation mechanism D having such an isocentric rotation function is configured as follows. A turn table 20b is installed on a floor face 5 at a position near an irradiation apparatus in such a manner that the upper surface of the turn table 20b is nearly at the same level (plane) as the upper plane of the floor face 5. An end portion of a rotational disk 20d is integrally mounted to the turn table 20b. A base 20c of a therapy bed 20 is mounted on the rotational disk 20d in such a manner that the therapy bed 20 is isocentrically rotatable around an axial center “r” of the turn table 20b. However, the use of such a function for an inspection apparatus for confirming and aligning the position of a lesion, for example, a CT scanner has been not examined. Even the above-described rotary bed 30 has an isocentric rotation mechanism upon use for an irradiation apparatus by means of a turn table installed on a floor face at a position on the irradiation apparatus side; however, the rotary bed 30 cannot make use of the isocentric rotation mechanism upon use for a CT scanner because the bed 30 is rotated around the center “r′”.
By the way, in a radiation therapy system in which the position of an affected portion is checked by a CT scanner and the affected portion is matched to an irradiation position of an irradiation apparatus, the alignment of the affected portion is mainly determined by the CT scanner used, and to most accurately perform the alignment of the affected portion by the CT scanner, it may be desirable to locate, at the time of scanning of the affected portion (lesion) by the CT scanner, the center of the affected portion at the center of a detectable region (a tunnel portion of a gantry) of the CT scanner. From this viewpoint, any related art CT scanner, which is capable of moving a bed, on which a patient to be irradiated lies, in the body-axis direction and of adjusting the height of the bed, fails to examine adjustment of the position of an affected portion of the patient in the lateral direction (right and left direction of the body of the patient).
The positional adjustment of the related art CT scanner will be described more fully with reference to FIG. 16. FIG. 16 is a typical view showing a gantry portion of a related art CT scanner 1′. As shown in this figure, in a tunnel portion (detectable region) 1c′ of a gantry 1b as a detector, the position of a CT bed 1a on which a patient B lies is adjusted, by vertical moving means (not shown), such that an affected portion (lesion) C is positioned at the center (shown by a chain line “j” in the figure) in the vertical direction (shown by an arrow “i” in the figure) of the tunnel portion 1c′. The position of the CT bed 1a in the tunnel portion 1c′ is also adjusted such that a cross-sectional plane of the patient, which plane contains the affected portion (lesion) C and is perpendicular to the body-axis, can be scanned. Such adjustment of the CT bed 1a is performed by configuring the CT bed 1a as a mobile type CT bed movable in the body-axis direction, or configuring the CT scanner 1′ as a mobile type CT scanner slid on moving rails installed on the floor face.
The related art CT scanner, however, fails to examine adjustment of the position of an affected portion in the right and left direction of the body of the patient, in a state that the patient lies on the bed, in the detectable region of the CT scanner, that is, in the direction perpendicular to the body-axis on the horizontal plane in the tunnel portion. In actual, since the diameter of the tunnel portion 1c′ of the gantry 1b is generally set to about 1 m, it is difficult to adjust the position of the affected portion, that is, the position of the bed on which the patient lies in the lateral direction. As a result, if the affected portion C is located, as shown by an imaginary line (two-dot chain line) in the figure, at the center (shown by a chain line “k” in the figure) in the lateral direction (shown by an arrow “f” in the figure) of the tunnel portion 1c′, the position of the affected portion C can be accurately checked; however, if the affected portion C is present at a side portion of the body of the patient B, and therefore, as shown by a solid line in the figure, the affected portion C is offset from the center (shown by the chain line “k” in the figure) of the lateral direction (shown by the arrow “f” in the figure) of the tunnel portion 1c′, the position of the affected portion in the lateral direction is checked by any marking. Such checking of the position of the affected portion in the lateral direction by marking is undesirable.